Server Hardware Components and Architecture
Server architecture questions test whether you can reason about the data path from CPU to storage and network, and about the components that can fail. Know the roles of CPU sockets, memory channels and DIMM population rules, PCIe lanes and slots, the baseboard management controller (BMC), power supplies, fans, and the front/rear I/O layout.
Important concepts: NUMA - memory attached to a socket is local to that socket, and remote access is slower; DIMM population order matters because unbalanced population reduces bandwidth or disables channels. PCIe generation determines per-lane bandwidth, and a card in a narrower or older slot runs at the lower capability. The BMC provides out-of-band management independent of the OS. Redundant PSUs share load and must be on separate power feeds to be meaningful.
Traps: assuming more DIMMs always means more bandwidth (population rules and channel balance matter); confusing core count with thread count; thinking a hot-swap fan means the server can run indefinitely with a fan removed; and forgetting that firmware/BIOS settings can cap memory speed or disable slots.
Worked example / rule of thumb: a two-socket server with 8 DIMM slots per socket and 4 memory channels per socket needs DIMMs distributed evenly across channels - populating all slots on one side leaves the other socket's memory remote. Rule of thumb: match the component's rated capability to the slot's capability; the system runs at the slowest link in the chain.